The invention relates to a hoisting device, particularly a block.
For numerous jobs and in particular for work carried out at a certain height such as the work carried out on overhead electric lines, hoisting devices are used which, in particular, comprise a pulley making it possible to lift a load.
The devices generally used satisfy only a single function--either the pulley serves as return pulley or the pulley forms a lowering pulley.
Since a long time there has been known a hoisting device, in particular a block formed of a case provided with a fastening member at its upper part, a pin, and a sheave movable on said pin and placed between the two sides of the case, corresponding to the preamble of claim 1.
These blocks, which satisfy the conditions for these two functions, are equipped with braking baffles around which the rope is partially wound. These braking baffles are located in the vertical extension of the return pulley and in the same vertical plane as the axis of symmetry of the pulley sheave. Therefore, there is a first disadvantage which consists in the substantial increase in length of the body of the block. Now it is very desirable that the block have as small a height as possible. Moreover, these devices have a hinged cover to provide access to the baffles. This cover must be locked in open position. On the other hand, it must in no case open or close without manual action by the operator. Furthermore the rope must be threaded by hand through the baffles, which presents certain difficulties in the case of cold or wet weather and, under the effect of distraction, in case of an accident.
With respect to these lowering blocks, indicated above, certain technical problems of not insignificant importance, have remained unsolved. One of these problems resides in the fact that the rope cannot be locked. Now it is undeniable that locking is of prime importance in certain cases of rescue.
Furthermore, the untimely opening of the baffle protection cover during a handling operation may cause the ejecting of the rope out of the baffle housing. This may result in a serious accident.
These various drawbacks make the correct functioning of these devices suspect, and accordingly their use is dangerous.